Systems and methods for switched multi-transducer pressure sensors and compensation thereof

ABSTRACT

Systems and methods are disclosed for a switched, multiple range sensor system including multiple transducers. In one embodiment, a method is provided that includes receiving and measuring at a first transducer and a second transducer, a pressure to generate a respective first and second pressure signal; amplifying the first and second pressure signals with corresponding first and second fixed-gain amplifier to generate first and second amplified pressure signals; selecting for monitoring, the first or second amplified pressure signal; converting the selected amplified pressure signal to an intermediate digital pressure signal; measuring, at a thermal sensor associated with the selected amplified pressure signal, a temperature; compensating, based on the measured temperature, the intermediate digital pressure signal to generate a compensated digital pressure output signal; and outputting the compensated digital pressure output signal.

FIELD

The disclosed technology relates to pressure transducers and moreparticularly to a sensor having multiple pressure transducers that canbe individually switched and selected according to the pressure rangebeing monitored. The disclosed technology further relates to asimplified scheme for compensating the transducers.

BACKGROUND

It is often necessary to measure pressure across a relatively largepressure range with a high degree of accuracy, where the accuracy istypically specified as a percent of full scale. A pressure transducercan be manufactured to have a high accuracy tolerance at full scale, butit can be relatively inaccurate when the measured pressure range is asmall fraction of the full scale. To partly address this issue, sensorscan be made with multiple transducers, each of which is optimized for aspecific portion of the pressure range. For example, it may be necessaryto measure a 10 PSI pressure to within 0.05 PSI at one time and thenlater measure a 500 PSI pressure to within 0.25 PSI at the samelocation. Certain conventional sensor systems may require two differentsensors and associated circuitry to make these measurements. However,such a measurement could be made with a multi-transducer sensor package,provided that the 10 PSI sensor that could withstand the 500 PSIpressure. Within the past several years it has become possible to use asingle, high-pressure sensor to more accurately measure a lower pressureusing a variety of signal processing techniques. The use of programmablegain amplifiers, digital thermal correction, and high accuracy analog todigital converters has enabled accuracies approaching 0.05% over anumber of different pressure ranges. For example, the same 500 PSIsensor could be used to measure ranges such as 0-10 PSI, 0-50 PSI, 0-100PSI, and 0-500 PSI.

These techniques work well and can be used for many applications;however, sensor noise can limit the use of the lower range of thesensor. Sensor noise level is influenced by many things, but in mostinstances the dominant source is thermal noise. For a typicalpiezoresistive sensor, thermal noise at a 10 kHz bandwidth is 0.005%.This can be lowered by reducing the bandwidth; however, in order to be auseful sensor, some bandwidth is needed and not all noise sources arebandwidth dependent. The lower floor of noise level is approximately0.001% which means that a sensor can usefully be re-ranged to no morethan about one tenth its full-scale range. A need still exists forsensor systems and methods that can measure a wide pressure range withhigh accuracy.

BRIEF SUMMARY

Some or all of the above needs may be addressed by certainimplementations of the disclosed technology. Certain implementations ofthe disclosed technology may include systems and methods for a switched,multiple range sensor system including multiple transducers having asimplified compensation scheme.

In one example implementation, a method is provided that includesreceiving and measuring at a first transducer and a second transducer, apressure to generate a respective first and second pressure signal;amplifying the first and second pressure signals with correspondingfirst and second fixed-gain amplifiers to generate first and secondamplified pressure signals; selecting for monitoring, the first orsecond amplified pressure signal; converting the selected amplifiedpressure signal to an intermediate digital pressure signal; measuring,at a thermal sensor associated with the selected amplified pressuresignal, a temperature; compensating, based on the measured temperature,the intermediate digital pressure signal to generate a compensateddigital pressure output signal; and outputting the compensated digitalpressure output signal.

In another example implementation, a system is disclosed. The system caninclude a first pressure transducer associated with a first pressurerange and configured to receive and measure a pressure to generate afirst pressure signal; a second pressure transducer associated with asecond pressure range and configured to receive and measure the pressureto generate a second pressure signal; a first fixed-gain amplifierconfigured to amplify the first pressure signal to generate a firstamplified pressure signal; a second fixed-gain amplifier configured toamplify the second pressure signal to generate a second amplifiedpressure signal; a multiplexer in communication with the first andsecond fixed-gain amplifiers, wherein the multiplexer is configured toreceive a selection signal to select, for monitoring, the first orsecond amplified pressure signal; an analog-to-digital converterconfigured to convert the selected amplified pressure signal to anintermediate digital pressure signal; at least one thermal sensorconfigured to measure and output a temperature signal associated withone or more of the first pressure transducer and the second pressuretransducer; and a microprocessor configured to: receive the intermediatedigital pressure signal; receive the temperture signal; compensate,based on the received temperature signal, the intermediate digitalpressure signal to generate a compensated digital pressure outputsignal; and output the compensated digital pressure output signal.

Other implementations, features, and aspects of the disclosed technologyare described in detail herein and are considered a part of the claimeddisclosed technology. Other implementations, features, and aspects canbe understood with reference to the following detailed description,accompanying drawings, and claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a circuit block diagram of a multiple-range sensor assembly100 including a multiplexer 103 for transducer selection and aprogrammable amplifier 105 for amplifying the selected signal, accordingto an example implementation of the disclosed technology.

FIG. 2 is a circuit block diagram of a multiple-range sensor assembly200 for automatic re-ranging, according to an example implementation ofthe disclosed technology.

FIG. 3 is a circuit block diagram of a multiple-range sensor assembly300 including a fixed amplifier for each transducer, according to anexample implementation of the disclosed technology.

FIG. 4 is a simplified block diagram of a multiple-range sensor assembly300 as shown in FIG. 3, according to an example implementation of thedisclosed technology.

FIG. 5 illustrates an example of how an applied pressure (x-axis) may bemeasured, digitized, and output (y-axis) for both a low-pressure-rangefirst transducer (upper curves) and a relatively higher-pressure-rangesecond transducer (lower curves), according to an example implementationof the disclosed technology.

FIG. 6 illustrates an example for compensating the output of a selectedtransducer to reduce or eliminate a non-linear response as a function ofthe applied pressure, according to an example implementation of thedisclosed technology.

FIG. 7 illustrates an example for compensating the output of a selectedtransducer for both temperature and non-linearity, according to anexample implementation of the disclosed technology. In certain exampleimplementations, the temperature alone may be compensated.

FIG. 8 is a flow diagram 800 of a method, according to an exampleimplementation of the disclosed technology.

DETAILED DESCRIPTION

Certain example implementations of the disclosed technology utilize asensor having multiple sensing transducers with appropriate switchingand conditioning to provide a continuous output proportional to theapplied pressure over a large pressure range with significantly enhancedaccuracy. Certain disclosed embodiments utilize multiple pressuretransducers, each of which is optimized for a specific portion of thepressure range and each of which is selected according to the pressurerange being measured.

Certain example implementations may utilize range downscaling, forexample, to digitally re-range the sensor output signal according to theapplied pressure range. Certain example implementations may utilizemultiple transducers, each of which can be individually re-ranged. Forinstance a 500 PSI transducer and a 50 PSI transducer can be included inthe same sensor package. This allows for each sensor to be used over asmaller dynamic range, and may provide an increased bandwidth and ahigher signal to noise ratio. Certain example implementations provideindividual sensors that are capable of extreme over-pressure conditions,which may allow the lower pressure-range sensors to operate withoutdamage, even when the measured pressure is at or above the maximum rangeof the higher pressure-range sensors. In certain exampleimplementations, each transducer of the sensor may include a temperaturesensor for measuring the transducer temperature. In certain exampleimplementations, each transducer may be equipped with its own fixed gainamplifier. In certain example implementations, temperature correctionmay be applied to the sensor output signal by utilizing thermalcorrection coefficients, look-up tables, and/or curves. In certainexample implementations, the use of the fixed gain amplifiers may enablethermal correction of a digitally re-ranged signal.

Some implementations of the disclosed technology will be described morefully hereinafter with reference to the accompanying drawings. Thisdisclosed technology may however, be embodied in many different formsand should not be construed as limited to the implementations set forthherein.

FIG. 1 is a block diagram of an example multiple range sensor assembly100, which includes a plurality of transducers including a firsttransducer 101 and at least a second transducer 102. According to anexample implementation of the disclosed technology, the transducers 101102 may be configured to measure a pressure. In certain exampleimplementations of the disclosed technology, the transducers 101 102 mayfurther be in communication with respective temperature sensors 110 111.The sensor assembly 100 may further include a multiplexer 103 incommunication with a microprocessor 104. The microprocessor 104 may beconfigured to communicate with the multiplexer 103, for example, toselectively couple (to the multiplexer 103 output) one of (1) a pressuresignal 120 from the first transducer 101, (2) a pressure signal 124 fromthe second transducer 102, (3) a temperature signal 122 associated withthe first transducer 101, or (4) a temperature signal 126 associatedwith the second transducer 102. In an example implementation, aprogrammable gain amplifier (PGA) 105 may be utilized to amplify and/orcondition the selected signal. In certain example implementations of thedisclosed technology, the microprocessor 104 may provide instructions tothe PGA, for example, to selectively set the gain and/or offset to aparticular value as appropriate for the desired range and transducer ortemperature measurement combination.

In accordance with an example implementation of the disclosedtechnology, the amplified analog signal from the PGA 105 may beconverted to a digital signal by an analog-to-digital converter (A/D)106 before being input to the microprocessor 104. In someimplementations, the A/D 106 may be part of the microprocessor 104. Incertain example implementations of the disclosed technology, one or bothof the PGA 105 and the A/D 106 may be implemented in the microprocessor104. In an example implementation, the specifications of the A/D 106 canbe selected based on the needed bandwidth, signal to noise ratio,resolution, and other factors.

In an example implementation, the microprocessor 104 may output adigital signal representation of the pressure measurement signalcorresponding to the selected transducer 101 102, and this signal can bereconverted to an analog signal for output by a digital-to-analogconverter (D/A) 107. In certain example implementations of the disclosedtechnology, the D/A 107 may provide a voltage or milliamp signal withappropriate signal conditioning. In certain example implementations ofthe disclosed technology, output from the microprocessor 104 can also beoutput in a digital format such as Ethernet, RS-485, CAN, etc. Incertain example implementations of the disclosed technology, an optionalbuffer 108 can be utilized to buffer a digital signal for output.

In accordance with an example implementation of the disclosedtechnology, the temperature sensors 110 111, as discussed above, may bethermistors or resistors (such as high TC resistors) having knowntemperature-related resistance characteristics. In an exampleimplementation, the temperature sensors 110 111 may form part of avoltage divider circuit so that a temperature of the correspondingtransducer can be determined by reading a voltage 122 across the dividercircuit. For example, the first temperature sensor 110 may form avoltage divider with a bridge resistor 115 associated with the firsttransducer 101. In certain example implementations of the disclosedtechnology the bridge resistor 115 may be designed to have a lowtemperature coefficient (low TC) while the temperature sensor 110 mayhave a high TC. In this way, temperature may predominately affect onlyone of the resistors in the voltage divider. Certain exampleimplementations of the disclosed technology may utilize additionalcomponents in the temperature sensor circuit, and other switchingconfigurations by the multiplexor 103 may be utilized without departingfrom the scope of the claimed technology.

In accordance with an example implementation of the disclosedtechnology, the multiplexer 103 may be switched (for example, by themicroprocessor 104) to connect input “A” to output “D” and input “B” tooutput “E” on the multiplexer 103. In accordance with an exampleimplementation of the disclosed technology, the microprocessor 104 mayutilize the temperature information to compensate the output signal forthermal effects, as will be further explained with respect to FIGS. 3-7below.

As discussed with respect to FIG. 1, certain components in the signalchain (i.e., the PGA 105, A/D 106, microprocessor 104, etc.) can be usedfor both pressure and temperature measurements by utilization of themultiplexer 103 to select the desired signal path(s). For example, in afirst time period, the first temperature signal 122 may be selected viathe multiplexer 103 and the PGA 105 and A/D 106 can further process theselected signals. Then in a second time period, the first pressuresignal 120 may be selected via the multiplexer 103, and the same PGA 105and A/D 106 can be utilized to process this signal without requiringadditional components. However, this approach may limit the speed of thedata acquisition when the multiplexer 103 switches between therespective ports to make the pressure and temperature measurements.Therefore, this approach, as discussed with respect to FIG. 1, may bebest applied for relatively low bandwidth applications.

In certain example implementations of the disclosed technology, themicroprocessor 104 may receive user input for appropriated ranging. Forexample, a user may input an indication to the microprocessor 104 toselect the full scale range to be either a first value (such as 10 PSIfor example, via selection of the first transducer 101) or a secondvalue (such as 500 PSI for example, via selection of the secondtransducer 102). In this example implementation, the microprocessor mayadjust the signal chain appropriately by selecting the appropriatetransducer 101 102. It should be noted that for this and all otherembodiments disclosed herein that some of the individual components, asdepicted in FIG. 1 may be part of a single system-on-a-chip (SOC) orField Programmable Gate Array (FPGA), rather than as separate integratedcircuits and components.

FIG. 2 is a block diagram of a multiple range sensor assembly 200 forautomatic re-ranging, according to an example implementation of thedisclosed technology. This embodiment is similar to the embodiment shownin FIG. 1, except for the highest range sensor 201 has a dedicatedsignal chain with its own dedicated PGA 205A and dedicated A/D 206A.This allows for the microprocessor 204 to make two pressure measurementssimultaneously. For example, the first measurement can be a highaccuracy measurement of the user selected range (for example, using aselected transducer 202), while the second measurement may be made bythe highest range sensor (using transducer 201, for example). In anexample implementation, this second measurement does not need to beextremely accurate, as it can be used as a secondary measurement todetermine the pressure when the first measurement pressure is out ofrange of the selected transducer 202.

To highlight differences between the second embodiment as shown in FIG.2 and the first embodiment as shown in FIG. 1, if the sensor in thefirst embodiment is set for 0-10 PSI and the pressure goes to 15 PSI,there may be no way for the user to know that the actual pressure hasgone out of range, so the pressure measurement may be inaccurate.However, as shown in FIG. 2, the highest-range transducer 201 may beused to monitor the pressure so that an appropriately ranged transducermay be manually or automatically selected for the measurement via themultiplexer 203, then appropriately conditioned via the common PGA 205B,and the common A/D 206B.

In certain applications, the output from the sensor assembly 200 can beanalog or semi-analog to support legacy systems (such as HART where theuser may not necessarily realize the sensor is out of range or be ableto re-range the sensor). In an example implementation, the multiplexer203 may select the appropriate transducer 202 to keep the mainmeasurement chain at the lower range (for example, 0-10 PSI range) whileusing the higher range sensor 201 to measure with reasonable accuracythe actual value of the pressure. In this implementation, an alert maybe sent to the user when the reading is out of range of the selectedtransducer 202. This way the user can re-range the system to theappropriate range without losing any data.

FIG. 3 is a block diagram of a multiple range sensor assembly 300including a fixed amplifier 305 306 for each transducer 301 302, amultiplexer 303 for transducer selection, and a microprocessor 304 fortransducer selection and compensation, according to an exampleimplementation of the disclosed technology. Thermal sensors 110 111 mayalso be utilized in this implementation to compensate fortemperature-related errors, as discussed with reference to FIG. 1, andas will be further discussed below.

In the implementation shown in FIG. 3, the fixed gain amplifiers 305 306may be used to acquire the raw data from the respective transducers 301302. For example, when a user selects a different pressure range, themicroprocessor may select (via the multiplexer 303) the transducer thatis appropriate for the selected range. For instance, if the firsttransducer 301 has a 100 PSI range and the second transducer 302 has a500 PSI range, and the user chooses a range of 50 PSI, themicroprocessor 304 may select the 100 PSI transducer 301 via themultiplexer 303.

In certain example implementations, each of the transducers 301 302 maybe energized when the sensor assembly 300 is powered-up and themultiplexer 303 may be utilized to select the appropriate (amplified)transducer signal. In such example implementations, energizing/biasvoltage(s) may applied to each of the transducers 301 302 and therespective signals from each of the respective transducers 301 302 andamplifiers 305 306 may be continuously available for selectivemonitoring based on user selection or appropriate input pressure rangesmatched to the capability of the given transducer 301 302.

In certain example implementations, and as depicted by the dashed linesin FIG. 3 (indicating alternative embodiments), the transducers 301 302may be selectively energized. For example, switches S1 S2 may becontrolled by the microprocessor 304 to selectively energize thetransducers 301 302 with respective energizing voltages V1 V2. Incertain example implementations, the energizing voltages V1 V2 may bethe same voltage. In other example implementations, the energizingvoltage V1 V2 may be different and configured for the particularrespective transducer 301 302.

In accordance with an example implementation of the disclosedtechnology, the pressure signal measured by the 100 PSI transducer 301may be amplified via a first amplifier 305 with a fixed gain; howeverthe signal may be digitally processes such that a full scale of 50 PSIis used. For example, the microprocessor 304 may use the same thermalcorrection coefficients for the transducer 301 that it would use if thefull scale range was 100 because the transducer 301 and analog signalchain is unchanged. According to an example implementation of thedisclosed technology, the microprocessor 304 may range the analog outputso that 50 PSI is the full scale output. Accordingly, the use of amulti-transducer, multi-range sensor system 300 may provide enhancedflexibility and may allow a user to stock fewer sensor types and to usethe same sensor type in many different installations.

FIG. 4 is a simplified block diagram of a multiple-range sensor assembly300, as shown in FIG. 3, according to an example implementation of thedisclosed technology. The various component representations 107 110 111301 302 303 304 305 306 308 are shown in FIG. 4, with descriptions forthese corresponding components discussed above with respect to FIG. 3.FIG. 4 also depicts a compensation module 402 in communication with themicroprocessor 304. As will be discussed below with reference to FIGS.6-7, the compensation module 402 may include a thermal compensationmodule configured to compensate the (digital and/or analog) output fortemperature affects based on a reading of the thermal sensors 110 111.In certain example implementations, the compensation module 402 mayfurther compensate the output for non-linear response of the transducers301 302, and will be discussed below with referenced to FIG. 6. Inaccordance with an example implementation of the disclosed technology,the compensation module 402 may be embodied in firmware or software, andprocessed by the microprocessor 304. In certain example implementations,the compensation module 402 may include memory for storing compensationcurves, coefficients, and/or a compensation look-up-table.

FIG. 5 provides illustrative examples of how an applied pressure(x-axis) may be measured, digitized, and output (y-axis) for both alow-pressure-range first transducer (upper curves) and a relativelyhigher-pressure-range second transducer (lower curves). For example, andto further illustrate the example provided above with respect to FIGS.3-4, the first transducer (such as transducer 301 in FIGS. 3-4) may havea 100 PSI full-scale range while the second transducer (such astransducer 302 in FIGS. 3-4) may have a 500 PSI full scale range. Inthis example illustration, amplified analog pressure signals (forexample, from the output of the respective fixed amplifiers 305 306 inFIGS. 3-4) are illustrated by the respective solid curves 506 502, whilethe corresponding digitized signals (such as may be provided at theoutput of the A/D converter 308 after selection of the transducer by themultiplexer 303, as shown in FIGS. 3-4) are illustrated by therespective dashed curves 508 504.

Also depicted in FIG. 5 (for illustration purposes only) is exaggeratednon-linear transducer responses as a function of the applied pressure(x-axis). However, certain example transducer implementations may resultin different response curves without departing from the scope of thedisclosed technology. Furthermore, to illustrate the exampleinterrelations among the applied pressure range, the selectedtransducer, and the resulting digitized signal (for example, asdiscussed above with reference to the A/D 308 in FIGS. 3-4), thedigitized output signals 508 504 are illustrated as if they weregenerated using a low-resolution, 4-bit (16 levels), 10-volt full-scaleA/D converter. However, in practice, a higher-resolution A/D converter,such as a 12-bit (or higher) A/D converter may be utilized.

The resolution of an A/D converter is a function of how many parts themaximum signal can be divided into. The formula to calculate resolutionis 2^(n). For example, a 12-bit A/D has a resolution of 2¹²=4,096, withthe best resolution being 1 part out of 4,096, or 0.0244% of the fullscale. Resolution of the A/D can limit the precision of a measurement.The higher the resolution (number of bits), the more precise themeasurement. Returning to the example of FIG. 5, the example 4-bit A/Ddivides the vertical range of the signal from the transducers into 16discrete levels with respect to the full-scale vertical range. With avertical range of 10 V, the 4-bit A/D cannot ideally resolve voltagedifferences smaller than 625 mV, as shown by the discreet levels in thedigitized output signals 508 504. In comparison, a 14-bit A/D converterwith 16,384 discrete levels can ideally resolve voltage differences assmall as 610 μV.

The curves shown in FIG. 5 illustrate how a properly ranged and properlyselected transducer can help reduce uncertainty in a measurement. Forexample, assume that an applied pressure has a range of about 0 to about100 PSI. If a 500 PSI transducer is used to measure this appliedpressure (as shown in the bottom curve 502), the resulting digitizedoutput 504 (using the exaggerated digitizing example utilizing a 4-bitA/D) in the mid portion of the applied pressure range may have asignificant uncertainty 510 of about 25 PSI, with even worse uncertaintyat higher pressure levels due to the example non-linear response of thetransducer. In contrast, if a (better matched) 100 PSI transducer isselected, the resulting mid-range uncertainty 512 may be reduced toabout 5 PSI since the full range of the A/D is being utilized.

According to an example implementation of the disclosed technology, amultiplexer (such as multiplexer 303 in FIGS. 3-4) may be switched toselect a given transducer's amplified output such that the selectedtransducer is appropriately matched with the range of the appliedpressure. In certain example implementations, if the applied pressurerange is greater than the measurable range of the selected transducer,the next higher range pressure transducer in the multi-transducer sensormay be selected. In certain example implementations, a microprocessormay switch the multiplexer to sequentially monitor the plurality oftransducers, and the appropriately-ranged transducer may then beautomatically selected for primary monitoring based on the relativelevels of the monitored transducers. In certain example implementations,the user may manually select the transducer for monitoring input appliedpressure.

FIG. 6 provides an illustrative example for compensating the output of aselected transducer to reduce or eliminate a non-linear response as afunction of the applied pressure. In accordance with an exampleimplementation of the disclosed technology, a microprocessor (such asmicroprocessor 104 204 or 304 as shown in the previous figures) may beutilized to perform the compensation. In this example illustration, themeasured response 602 may be in the form of a digitized pressure signal(for example, from the output of the A/D converter 308 in FIGS. 3-4) andit may be received by the microprocessor (for example, themicroprocessor 304 in FIGS. 3-4). According to an example implementationof the disclosed technology, a known compensation 604 may be applied tothe measured response 602 to result in a compensated output signal 606,which in certain example implementations may a linearized digital outputsignal. As may be appreciated in this example, the A/D converter (suchas the A/D 308 as shown in FIGS. 3-4) may have a much higher resolution(for example, 14-bit) than shown in the example presented above withrespect to FIG. 5 in which the example A/D resolution was set to 4-bitsfor illustration purposes only. Thus, the quantization effects of theA/D may still be present in the measured response 602, but suchquantization may be reduced with a high-resolution A/D to the pointwhere the non-linear compensation may provide additional measurementaccuracy. In certain example implementations, compensation fornon-linear response of the transducer may be handled by an externalprocessor or module. In yet other example implementations, temperatureand/or non-linear compensation can be performed, as will be discussedbelow with reference to FIG. 7.

FIG. 7 illustrates compensating the output of a selected transducer forboth temperature and non-linearity. However, in certain exampleimplementations, the temperature alone may be compensated. As discussedabove with respect to FIG. 6, and in accordance with an exampleimplementation of the disclosed technology, a microprocessor (such asmicroprocessor 104 204 or 304 as shown in the previous figures) may beutilized to perform the compensation. In this example illustration, ameasured response 602 (for example, from the output of the A/D converter308 in FIGS. 3-4) may be received by the microprocessor (for example,the microprocessor 304 in FIG. 3-4) and known temperature compensationvalues 702 may be applied to the measured response 602 based on themeasured temperature (T1, T2, T3, etc.), resulting in correspondingtemperature-compensated output 704. For example, a specific compensationvalue may be selected based on the value of the measured response 602and the measured temperature, and this compensation value may be addedto (or subtracted from) the measured response 602 based on the monitoredtemperature to produce a corresponding compensated output signal 702. Incertain example implementations, the temperature sensors 110 111, asdiscussed above with respect to FIGS. 1-4 may be utilized for monitoringthe temperature of the respective transducer, and may be utilized forselection of the temperature compensation values.

As may be appreciated by those having skill in the art, the embodimentas shown in at least FIG. 3 and discussed with reference to FIGS. 4-7allows for a simplified and reliable compensation process of theselected transducer 301 302 by virtue of the fixed-gain amplifiers 305306. In other words, since the amplifiers 305 306 have fixed gain, thesignal chain from the transducers 301 302 through the amplifiers 305 306and through the multiplexer 303 and A/D 308 remain consistent, andtherefore, the microprocessor 304 can utilize consistent compensationcurves without having to account for the extra complexity of changinggains in the signal path, such as may be the case in the embodimentsshown in FIG. 1 and FIG. 2, which use programmable gain amplifiers.

FIG. 8 is a method flow diagram 800 according to an exampleimplementation of the disclosed technology. In block 802, the methodincludes receiving, at a first transducer and a second transducer, apressure, wherein the first transducer is associated with a firstpressure range and the second transducer is associated with a secondpressure range. In block 804, the method includes measuring, at thefirst transducer, the pressure to generate a first pressure signal. Inblock 806, the method includes amplifying the first pressure signal witha first fixed-gain amplifier to generate a first amplified pressuresignal. In block 808, the method includes measuring, at the secondtransducer, the pressure to generate a second pressure signal. In block810, the method includes amplifying the second pressure signal with asecond fixed-gain amplifier to generate a second amplified pressuresignal. In block 812, the method includes selecting for monitoring, thefirst or second amplified pressure signal. In block 814, the methodincludes converting the selected amplified pressure signal to anintermediate digital pressure signal. In block 816, the method includesmeasuring, at a thermal sensor associated with the selected amplifiedpressure signal, a temperature. In block 818, the method includescompensating, based on the measured temperature, the intermediatedigital pressure signal to generate a compensated digital pressureoutput signal. In block 820, the method includes outputting thecompensated digital pressure output signal.

In accordance with an example implementation, the disclosed technologycan include converting the compensated digital pressure output signal toan analog output signal and outputting the analog output signal.

In an example implementation, the selecting for monitoring can includedetermining, based on the intermediate digital pressure signal, whetherthe received pressure corresponds to the first pressure range or thesecond pressure range. Responsive to determining that the receivedpressure corresponds to the first pressure range, certain exampleimplementations can include selecting the first amplified pressuresignal as the selected amplified pressure signal; and responsive todetermining that the received pressure corresponds to the secondpressure range, selecting the second amplified pressure signal as theselected amplified pressure signal.

In certain example implementations, the selecting may be performed, atleast in part, by sequentially reading the first and second intermediatedigital signals.

In an example implementation, the selecting may be based on a comparisonof one or more of the first and second intermediate digital signals withone or more of the first and second pressure ranges associated with thecorresponding first and second transducers.

In certain example implementations, the selecting may be performedresponsive to a selection indication provided by a user.

According to an example implementation, the disclosed technology canfurther include compensating the intermediate digital pressure signalbased on a predetermined non-linearity of the associated first or secondtransducer to generate a linearized compensated digital pressure outputsignal.

In an example implementation, the first pressure range may be asub-range of the second pressure range.

In an example implementation, the second pressure range may be differentfrom the first pressure range.

Certain example implementations can include outputting an overpressureindication when one or more of the intermediate digital pressure signaland the compensated digital pressure output signal exceed correspondingpredetermined values.

In certain example implementations, each of the first pressuretransducer and the second pressure transducer may include a diaphragmthat is part of a piezoresistive array.

In certain example implementations of the disclosed technology, one ormore of the transducers may be utilized to measure a pressure signal,for example, without requiring that each transducer of themultiple-transducer sensor continues to generate a pressure signal oramplified pressure signal when not selected. For example, oneimplementation can include receiving, at a first transducer and a secondtransducer, a pressure, wherein the first transducer is associated witha first pressure range and the second transducer is associated with asecond pressure range; measuring, at one or more of the first transducerand the second transducer, the pressure to generate one or more of afirst pressure signal and a second pressure signal; amplifying the oneor more of the first pressure signal and the second pressure signal withone or more of a first fixed-gain amplifier and a second fixed gainamplifier to generate one or more of a first amplified pressure signaland a second amplified pressure signal; selecting for monitoring, thefirst or second amplified pressure signal; converting the selectedamplified pressure signal to an intermediate digital pressure signal;measuring, at a thermal sensor associated with the selected amplifiedpressure signal, a temperature; compensating, based on the measuredtemperature, the intermediate digital pressure signal to generate acompensated digital pressure output signal; and outputting thecompensated digital pressure output signal.

It should be clear from the disclosed technology that a multiple rangetransducer may be implemented by utilizing multiple transducers,appropriate amplifiers, multiplexing circuitry, A/D (and D/A) convertersand at least one microprocessor. In accordance with an exampleimplementation of the disclosed technology, each of the multipletransducers can be designed to accurately accommodate a given pressurerange and can be employed to produce an output when the applied pressureis within that range. In this manner, the most accurate and efficientsensor may be used for each of the plurality of pressure ranges to bemeasured, therefore, providing a high degree of accuracy across arelatively large pressure range.

In accordance with an example implementation of the disclosedtechnology, the use of fixed-gain amplifiers with each correspondingtransducer may provide the additional technical benefit of enabling asimplified compensation scheme to correct for temperature and/ortransducer non-linearity. It should be apparent to one skilled in theart that there are many alternate ways of accomplishing the disclosedtechnology, all of which are deemed to be encompassed within the spiritand claims appended hereto.

What is claimed is:
 1. A method, comprising: receiving, at a firsttransducer and a second transducer, a pressure, wherein the firsttransducer is associated with a first pressure range and the secondtransducer is associated with a second pressure range; measuring, at thefirst transducer, the pressure to generate a first pressure signal;amplifying the first pressure signal with a first fixed-gain amplifierto generate a first amplified pressure signal; measuring, at the secondtransducer, the pressure to generate a second pressure signal;amplifying the second pressure signal with a second fixed-gain amplifierto generate a second amplified pressure signal; selecting formonitoring, the first or second amplified pressure signal; convertingthe selected amplified pressure signal to an intermediate digitalpressure signal; measuring, at a thermal sensor associated with theselected amplified pressure signal, a temperature; compensating, basedon the measured temperature, the intermediate digital pressure signal togenerate a compensated digital pressure output signal; and outputtingthe compensated digital pressure output signal.
 2. The method of claim1, further comprising: converting the compensated digital pressureoutput signal to an analog output signal; and outputting the analogoutput signal.
 3. The method of claim 1, wherein the selecting formonitoring comprises: determining, based on the intermediate digitalpressure signal, whether the received pressure corresponds to the firstpressure range or the second pressure range; and responsive todetermining that the received pressure corresponds to the first pressurerange, selecting the first amplified pressure signal as the selectedamplified pressure signal; and responsive to determining that thereceived pressure corresponds to the second pressure range, selectingthe second amplified pressure signal as the selected amplified pressuresignal.
 4. The method of claim 1, wherein the selecting is performed, atleast in part, by sequentially reading the first and second intermediatedigital signals.
 5. The method of claim 1, wherein the selecting isbased on a comparison of one or more of the first and secondintermediate digital signals with one or more of the first and secondpressure ranges associated with the corresponding first and secondtransducers.
 6. The method of claim 1, wherein the selecting isperformed responsive to a selection indication provided by a user. 7.The method of claim 1, further comprising compensating the intermediatedigital pressure signal based on a predetermined non-linearity of theassociated first or second transducer to generate a linearizedcompensated digital pressure output signal.
 8. The method of claim 1wherein the first pressure range is a sub-range of the second pressurerange.
 9. The method of claim 1, wherein the second pressure range isdifferent from the first pressure range.
 10. The method of claim 1,further comprising outputting an overpressure indication when one ormore of the intermediate digital pressure signal and the compensateddigital pressure output signal exceed a predetermined value.
 11. Asystem, comprising: a first pressure transducer associated with a firstpressure range and configured to receive and measure a pressure togenerate a first pressure signal; a second pressure transducerassociated with a second pressure range and configured to receive andmeasure the pressure to generate a second pressure signal; a firstfixed-gain amplifier configured to amplify the first pressure signal togenerate a first amplified pressure signal; a second fixed-gainamplifier configured to amplify the second pressure signal to generate asecond amplified pressure signal; a multiplexer in communication withthe first and second fixed-gain amplifiers, wherein the multiplexer isconfigured to receive a selection signal to select, for monitoring, thefirst or second amplified pressure signal; an analog-to-digitalconverter configured to convert the selected amplified pressure signalto an intermediate digital pressure signal; at least one thermal sensorconfigured to measure and output a temperature signal associated withone or more of the first pressure transducer and the second pressuretransducer; and a microprocessor configured to: receive the intermediatedigital pressure signal; receive the temperture signal; compensate,based on the received temperature signal, the intermediate digitalpressure signal to generate a compensated digital pressure outputsignal; and output the compensated digital pressure output signal. 12.The system of claim 11, further comprising a digital-to-analog converterconfigured to convert an output of the microprocessor to an analogsignal.
 13. The system of claim 11, wherein the microprocessor isfurther configured to: determine, based on the intermediate digitalpressure signal, whether the received pressure corresponds to the firstpressure range or the second pressure range; output to the multiplexer,the selection signal to select, for monitoring, the first amplifiedpressure signal responsive to determining that the received pressurecorresponds to the first pressure range; and output to the multiplexer,the selection signal to select, for monitoring, the second amplifiedpressure signal responsive to determining that the received pressurecorresponds to the second pressure range.
 14. The system of claim 11,wherein the microprocessor is further configured to output to themultiplexer, the selection signal to sequentially select the first andsecond amplified pressure signal and to sequentially read thecorresponding selected first and second intermediate digital signals.15. The system of claim 14, wherein the microprocessor is furtherconfigured to output to the multiplexer, the selection signal based on acomparison of one or more of the first and second intermediate digitalsignals with one or more of the first and second pressure rangesassociated with the corresponding first and second transducers.
 16. Thesystem of claim 14, wherein the microprocessor is further configured tocompensate the intermediate digital pressure signal based on apredetermined non-linearity of the associated first or second transducerto generate a linearized compensated digital pressure output signal. 17.The system of claim 14 wherein the first pressure range is a sub-rangeof the second pressure range.
 18. The system of claim 14, wherein thesecond pressure range is different from the first pressure range. 19.The system of claim 14, wherein the microprocessor is further configuredto output an overpressure indication when one or more of theintermediate digital pressure signal and the compensated digitalpressure output signal exceed a predetermined value.
 20. The system ofclaim 14, wherein each of the first pressure transducer and the secondpressure transducer comprise a diaphragm that is part of apiezoresistive array.